Prep pad Thai sauce before you start. (See below).
Bring a pot of salted water to the boil.
Add noodles to pot of boiling water, stir to separate noodles and cook for about 5 minutes, until just tender. Drain and refresh under cold water to cool. Toss with a drizzle of sesame oil to prevent sticking. Set aside.
Heat a drizzle of oil in a fry-pan or wok on medium-high heat. Add lemongrass, makrut lime leaf, mushrooms and spring onion and cook, stirring, for 4-5 minutes, until starting to brown.
Add cooked noodles, green beans, first measure of mung bean sprouts, tofu, pad Thai sauce and a drizzle of sesame oil. Mix to combine and cook a further 3-4 minutes, stirring, until noodles are well coated in sauce and hot through.
Serve noodles topped with peanuts, second measure of mung bean sprouts, chilli and mint.